Typical Plan Types of Flexible Housing Based on the Analysis of Variation Trends Bora LEE and HyunSoo LEE Department of Housing & Interior Design, Yonsei University, Seoul, Korea SooAm KIM Building Standard and System Group, Building Research Division, Korea Institute of Construction Technology Abstract: This research aims at suggesting suitable plantypes for flexible housing based the distinctive characteristics of the flexible aparttnent unit plans in Korea identified through the diachronic analysis of the variation trends. This study performs space analysis using the Space Syntax Model by quantifying the interrelationships among the spatial units each of which are designed to satisfy specific needs of residents. In this paper, 256 flexible unit plans are investigated to analyze the variation trends in flexible housing unit design. This study also identifies typical plan types for flexible housing based on the generalized variation trends. Keywords: Flexible unit planning, Variation trends, Space Syntax Model, Typical plan types 1. INTRODUCTION Residential needs frequently change according to the occupants' life cycles and their various life styles. However, standardized and mass-produced conventional housings are not flexible enough to satisfy residents' such demands. One of the ways to satisfy dynamic residential needs is to explore a flexible housing concept. Prefabrication may be considered for this purpose. Constructing an entire house through prefabrication is ideal but it practically is not feasible because of high construction cost and increased maintenance efforts. It is therefore necessary to analyze unit plan variation trends to identify multiple resident's needs to adapt the spaces in a house, accordingly. To identify more economical and rational residential unit plan variations, it is indispensable to know the set of spaces needed to be frequently adapted by the residents. The major goal of this research is to generalize the direction for the flexible floor planning based on the adaptation tendency in contemporary Korean residential unit plans. 2. RESEARCH SCOPE AND METHOD Significant numbers of cases are explored to analyze the trends in residential floor plan variations. The flexible apartment housing units studied in this research are limited to the interior spaces designed to be reorganized or the ones having at least more than one spatially controllable area between a bedroom and the other. These spaces are normally constructed with bearing wall structure, bearing wall plus column structure, beam and column structure, or flat slab structure for the division, removal or shifting of spaces with non-bearing wall, sliding door, or furniture-type wall. From the perspective of geographical distribution and construction year (the first year of actual dwelling), the investigated flexible unit plans have been constructed or will be constructed around Seoul metropolitan area during 1991 - 2005 period. Those housing units selected are introducing various flexible floor-planning features. As a result, total 256 cases are collected for the survey from various sources such as apartment floor plan brochures, catalogues, and web sites of the leading Korean construction companies. Flexible types, characteristics, and design trends are extracted from the collected cases based on a group of selection criteria such as area, front bay number, and the year of construction. As for area criterion, 60m1, 85m2, 102m2, 135m1, 165m2,and 180m2or more are considered. This research compared and analyzed the integration values for both before and after the floor plan variations along with the calculations of the frequencies and percentages of such variations. As a consequence, this research was able to produce a set of generalized typical plan types insightful for the flexible housing in the future. 3. OUTCOME OF THE ANAYSIS 3.1. Overview of the Collected Cases The magnitudes of flexible apartment housing constructions in Korea mapped onto time dimension show that the highest distribution is 34.4% (88 cases) in 2002. Significant portion of the examined cases, 63.7% (163 cases), were constructed during 2001-2003 period. Interestingly, the instances have increased rapidly since 2000 compared to 1990's and the un-built cases whose points of construction are after the year 2003 will be continuously constructed in the future, therefore, this tendency will likely be maintained. The frequencies of the collected flexible unit plan cases classified by area are in the decreasing order of 135m2(94 cases), 165 mZ(71cases), and 102m2(55cases). 85.9% (220 cases) of the collected flexible unit plan cases are below 85m2 and only small portion of the cases show 180m2 or more. The cross-analysis based on the year of construction and unit area reveals another interesting observation. The apartment units having the area of 165m2 and 102mz were dominant compared to the other unit sizes before and after 1994. In the mean time, the units with the area of 1 35mZhave increased rapidly before and after 2002 so that it became the most prevalent apartment unit type followed by the units the sizes of which are 1 65m2 and 102mZas is shown in Figure 1. 40 +above1 €?Us sr more 35 +165s3 3 0 I 355 3 25 : 1 025 t20 -8553 LL Year ofconstmctbn Figure I Distribution of the Cases Based on Year of Construction and Area 3.2. Characteristic Features of the Surveyed Flexible Unit Plans Table 1 shows flexible unit plan diagrams obtained from the survey. The diagrams are constructed based on the number and frequencies of variations as well as the bays in which variations are occurred. Table 1 Major Variation Types Nurnbcr of Plan Type FrrqurncyIBa~ Numbel of Plan Type FrequrncylBay Variation Variation 107 cases 3 cases appear appear in 2,3,4 2 in 4bays bays 87 cases 2 cases appear appear in 2,3,4 in 4bays bays 30 cases 4 2 cases appear appear in in 3bays 4bays 5 cases appear 1 case appears in 2,3 bays in 4bays 5 cases appear 1 case appears in 3 bays in 4bays 5 cases appear 1 case appears in 4 bays in 3,4bays R, R -* .E " Bedroom Variation between Bedroom and Bedroom L-Living Room R-R <R, Ri R, L> K-Kitchen Partition between Bedroom and D-Dining Room Bedroom 3 cases appear T-Toilet in 5 bays RR B-Bath Room Without Partition between d-Dress Room M-Multi Room Bedroom and Bedroom <R, R, L>- E- Entrance w Variation between Bedroom and Bedroom and variation between Bedroom and Living room I > pic:ll lJIl;1n I > pcs ot Plcxiblc I lo~isi~lg:B;~\ecl orr IItl. \11;1l\%is of' \ ariation I rend\ 3.3. Relational Analysis of the Flexible Floor Types by Area and Bay One of the characteristic features of the concurrent Korean residential unit plans is that there is a preferred typical unit proportion which usually is a rectangular form whose width is wider than its depth. The reason for this is that the construction companies focus on specific floor plans to attract customers by providing unique apartment units which have many bays (the number of bedrooms or living rooms adjacent to the front balcony) because more bays suggests better view and more daylight from outside. Hence, the preference profile shown by the frequencies for the different number of rooms close to front bay is more distinctive than that differentiated by the area since the major way of performing flexible planning is to transform the rooms adjacent to the front bay in most flexible apartment housing projects investigated (Figure 2). Figure 2 Flexible Unit Planning Distributions Based on Area (le3) and Front Bay (right) Frequency analysis of the flexible spaces classified by the area shows that the variation between a bedroom and a kitchen or the variation between a bedroom and a living room addresses 4 cases each and those cases appeared mostly as 60m2 type. 5 out of 7cases of 85m2 type are coupled with the variation between a bedroom and a living room. Variations happen not just between a bedroom and a living room; they are also performed between a bedroom and a kitchen and are implemented for the design of 3 bedrooms of 3LDK or for making a bedroom larger among a living room, a kitchen, or a dinning room of 2LDK. The variation that happens between a bedroom and a living room addresses 34 (61.8%) out of 55 cases of 102m2 type and the variation between a bedroom and another bedroom is represented in 14 cases. As the size of the bedroom adjacent to front area decreases due to a limited front area in 4 LDK, the choice of variation among 4 LDK, a large living room and 3 LDK, or a large bedroom and 3 LDK is occurred. Each of R, L type and R, R type takes 33 out of 94 cases in 135m2category; R, R, L type takes 21 cases; R, R type takes 31 cases (43.7%); R, L type takes 24 cases; R, R, L type takes 6 among 71 cases that are classified as 1651-11' type; R, R type and R, L type take 7 among 17 cases of over 180m2 type. For the floor unit plan having more than 135m2, it is important to make a large living room, however, it seems that the bedroom size is important matter ensuring more than 3 bedrooms. In general, as the area increases, the variation between a kitchen and a bedroom, the variation between a living room and the bedroom adjacent to the living room, and then the variation between a bedroom and an adjacent bedroom appear. It is found that the variation is directed to primarily control the size of the bedroom (Figure 3). Figure 3 Diagrammatized Flexible Unit Plan Types Based on Area As for the relationship between flexible unit types and the number of bays, the flexible planning between a bedroom and a living room generally happens in 3 bays, and the flexible planning between a bedroom and the other bedrooms marks the maximum frequency in 4 bays.